VPN speed issue

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eliottt
OpenVpn Newbie
Posts: 3
Joined: Thu Apr 15, 2021 4:52 pm

VPN speed issue

Post by eliottt » Thu Apr 15, 2021 5:10 pm

Hello,

I created a VPN on dedicated server (kimsuffit/OVH). The download speed from server to client is acceptable but upload speed is very weak.

I really don't understand where the problem is, I tested many many configurations form web topics and not any improve the speed.

On server/client side there is no cpu usage issue.

SPEED ON INTERNET:

Server speed (speed test.net): Serveur KS-3 - Atom N2800 - 4GB DDR3 1066 MHz - 2To SATA
Latency: 3.56 ms (0.69 ms jitter)
Download: 94.04 Mbps (data used: 42.4 MB)
Upload: 94.12 Mbps (data used: 42.4 MB)

client speed (speed test.net): Mac Book Pro 2009 - Core 2 DUO 2.8Ghz - 8GB - 512Go SSD
Latency: 17 ms
Download: 377 Mbps
Upload: 365 Mbps

CLIENT SPEED WITH VPN:

Latency: 20ms
Download: 30 Mbps AES-256-CBC / 28 Mbps AES-128-CBC / 38 Mbps non encryption
Upload: 8.4 Mbps AES-256-CBC / 8 Mbps AES-128-CBC / 13 Mbps non encryption

I lost a little with encryption but I think it's no significant because the speed still very low.

I played with many other parameters (plase find below my last config):

tun-mtu 6000
fragment 0
mssfix 0
txqueuelen 1000
;mssfix 1212
;link-mtu 3000
;tun-mtu 60000
;sndbuf 512000
;rcvbuf 512000
;push "sndbuf 512000"
;push "rcvbuf 512000"

I really don't know how to test anymore, do you think eg FTP transfert speed test between server and client can be a good test ?

I'm on debian 10.

Server configuration:
local x.x.x.x
port 17443
proto udp
dev tun
tun-mtu 6000
fragment 0
mssfix 0
txqueuelen 1000
ca /etc/openvpn/easy-rsa/pki/ca.crt
cert /etc/openvpn/easy-rsa/pki/issued/server.crt
key /etc/openvpn/easy-rsa/pki/private/server.key
dh /etc/openvpn/easy-rsa/pki/dh.pem
auth SHA256
tls-crypt /etc/openvpn/easy-rsa/pki/ta.key
;topology subnet
server 10.8.1.0 255.255.255.0
push "route 10.8.1.0 255.255.255.0"
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
cipher AES-128-CBC
ncp-disable
user nobody
group nogroup
persist-key
persist-tun
status /var/log/openvpn-status.log
log-append /var/log/openvpn.log
verb 3
Thank you for help.

User avatar
TinCanTech
OpenVPN Protagonist
Posts: 9018
Joined: Fri Jun 03, 2016 1:17 pm

Re: VPN speed issue

Post by TinCanTech » Thu Apr 15, 2021 8:01 pm

Try using --mtu-test

eliottt
OpenVpn Newbie
Posts: 3
Joined: Thu Apr 15, 2021 4:52 pm

Re: VPN speed issue

Post by eliottt » Fri Apr 16, 2021 4:33 pm

Hello,

there is the result, both client and server side:

NOTE: Empirical MTU test completed [Tried,Actual] local->remote=[1572,1572] remote->local=[1572,1572]

Thank you.

User avatar
TinCanTech
OpenVPN Protagonist
Posts: 9018
Joined: Fri Jun 03, 2016 1:17 pm

Re: VPN speed issue

Post by TinCanTech » Fri Apr 16, 2021 5:49 pm

Then you do not have an MTU problem and should not muck around with it.

eliottt
OpenVpn Newbie
Posts: 3
Joined: Thu Apr 15, 2021 4:52 pm

Re: VPN speed issue

Post by eliottt » Fri Apr 16, 2021 8:04 pm

Hello,

I tested with FTP and without VPN.

I can download up to 100Mbps (maximum of server speed) but still limited to 10Mbps on upload.

I think the problem came from my ISP or OVH.

Thank you for help.

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